readme fix

Author: nekufa

README.md

@@ -174,8 +174,9 @@ $mapper->getSpace('_vspace'); // no new requests are made
 ```
 
 ## Query Cache
-If you don't want to perform select queries you can inject cache interface to space instance/\
-For example, we use apcu adapter from `symfony/cache` package.
+If you don't want to perform select queries you can inject cache interface to space instance.\
+Use your favorite psr/cache implementation to persist schema on the application side.\
+For example, we use array adapter from `symfony/cache` package.
 ```php
 use Symfony\Component\Cache\Adapter\ArrayAdapter;